Re: Max anode voltage?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Ed Phillips <evp@xxxxxxxxxxx>

Original poster: David Speck <Dave@xxxxxxxxxxxxxxxx>

Robert,

If tubes are anything like light bulbs, you may take a significant 
hit on filament longevity by running them at 10% overvoltage.  I read 
somewhere that the life of an incandescent lamp varies as the inverse 
cube of the current, so that works out to about 75% of the rated lifetime.

Dave

With 10% more filament voltage you can probably double the saturation
current."

   I think that the effect of overvoltage on life is even greater 
than you state - there's information on it in my RCA Transmitting 
Tube handbook but it isn't handy right now.  Depends on the filament 
(pure tungsten, thoriated tungsten, oxide-coated, etc.).  On the 
other hand, life is probably not much of a consideration in TC work 
and some overvoltage is undoubtedly permissible.

Ed